Green Flash, Tenerife, Spanish Canary Islands
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Tony Cook imaged this flash from the island of Tenerife on October 24, '04. The sun is setting behind clouds. Tony was some 20-30ft above sea level and saw three green flashes during the one sunset. The flash is a variant of an M-Mir type produced by the miraging and magnifying effects of a vertically wavy inversion layer.     The 'smudge' to the left is the mirage distorted giant sunspot group #687.   More ↓

   The inversion layer in this case cannot be at constant height above the earth's surface because the flash is above the astronomical horizon. The layers here (there are several) are likely shaped by vertical waves in the atmosphere. The magnification necessary for a flash occurs where a line from the eye is tangential to the convex lower edge of the inversion. If part of the layer has a stronger curvature than that of the earth due to atmospheric waves the flash can occur above the astronomical horizon.

Andrew Young adds: "The red rim where the Sun meets the clouds is a nice example of [a coloured rim]. If you are far enough from the apparent horizon it will have a red line along it like this because of dispersion in the intervening atmosphere. The general raggedness of the solar limb here suggests that there might be breaking Kelvin-Helmholtz waves on some of the inversions."

Image ©2004 Tony Cook, reproduced with permission.